Condensed Balance Sheets (Unaudited) - USD ($) $ in Thousands	Sep. 30, 2015	Dec. 31, 2014
Current assets:
Cash and cash equivalents	$ 46,362	$ 54,059
Prepaid expenses and other current assets	653	342
Total current assets	47,015	54,401
Property and equipment, net	480	486
Restricted cash	94	94
Other assets	14	19
Total assets	47,603	55,000
Current liabilities:
Accounts payable	2,279	2,458
Accrued expenses	1,146	1,987
Notes payable, current portion	3,711	251
Deferred revenue	471	506
Total current liabilities	7,607	5,202
Other liabilities	275	4
Notes payable, net of current portion	11,023	9,749
Warrant liability	$ 33	$ 3,219
Commitments and contingencies
Stockholders’ equity:
Preferred stock, $0.001 par value per share; 5,000,000 shares authorized at September 30, 2015 and December 31, 2014 and no shares issued and outstanding at September 30, 2015 and December 31, 2014	$ 0	$ 0
Common stock, $0.001 par value per share; 200,000,000 shares authorized at September 30, 2015 and December 31, 2014 and 19,538,510 and 17,933,260 shares issued and outstanding at September 30, 2015 and December 31, 2014, respectively	20	18
Additional paid-in capital	143,518	128,558
Accumulated deficit	(114,873)	(91,750)
Total stockholders’ equity	28,665	36,826
Total liabilities and stockholders’ equity	$ 47,603	$ 55,000